(Update) MBTA probe hones in on Green Line operator

MBTA officials are considering all factors as to what caused a Green Line trolley to veer off the tracks Monday near Fenway Station, including speed.

A shot of the scene near Monday's Green Line derailment. Photo: Nicolaus Czarnecki/Metro

An investigation into what caused a Green Line trolley to derail Monday afternoon is narrowing in on the actions of the operator, who has been taken off the job as officials examine the circumstances of the accident.

Ten people were injured at 12:20 p.m. Monday — including the driver — when the Riverside-bound D line trolley veered off the tracks, causing another trolley to stop short behind it.

A thorough inspection of the track and signal systems revealed no defects nor anomalies, and preliminary testing found no mechanical issues with the trolley’s equipment, according to MBTA spokeswoman Kelly Smith.

"Investigators continue to take a close look at the performance of the motorperson who was operating the train at the time," Smith said Tuesday afternoon.

First responders assist a Green Line passenger after today's accident. Photo: Nicolaus Czarnecki/Metro

Although T officials said they will not name the operator, local news stations WCVB and CBS Boston identified the driver as 48-year-old Sydley Gardner, a five-year employee with a history of spotty driving.

The Globe reported Thursday that Gardner was fired in 2010 after he failed to report a previous collision with a pedestrian.

However the T was forced to rehire Gardner after an arbitrator ruled in his favor, said MassDOT Secretary Richard Davey.

“Obviously, I disagreed with the arbitrator’s decision. If not, I wouldn’t have moved to terminate him,’’ said Davey, who was MBTA general manager at the time.

Gardner reportedly has a slew of motor vehicle driving infractions in records from the Massachusetts Registry of Motor Vehicles.

The infractions allegedly include speeding, failure to stop and several license suspensions for failure to make required payments, WCVB reported.

When asked if speed was a factor in the crash, Smith said, “It is certainly among the factors being considered but the investigation continues. No concrete determinations have been made at this time.

“The MBTA is conducting the investigation, which will take as long as is necessary to establish all the facts,” said Smith.

Boston EMS spokesman Nick Martin said 10 patients were transported following the derailment, “all with relatively minor injuries.” MBTA spokesman Joe Pesaturo said Monday that many victims were complaining of back pain.

Service on the D and C branches were suspended through Monday evening, though crews were able to restore Green Line service in time for the Tuesday morning commute.

One trolley passenger captured an 11-second video of the aftermath and posted it on YouTube.

The man, who asked to be identified as Vin, said in his video description that “the front cart got derailed and crashed into the wall. Luckily almost everyone was seated. … Everyone seems to be fine aside from a few people feeling light headed.”